The present application claims priority under 35 U.S.C. xc2xa7 119 of German Patent Application No. 197 41 517.2, filed on Sep. 20, 1997, the disclosure of which is expressly incorporated by reference herein in its entirety.
1. Field of the Invention
The present invention relates to a method to reduce adhesion of a damp web, e.g., paper, textile, or other fibrous material web, to a rotating roll.
2. Discussion of Background Information
Due to the ever-increasing speeds of machines for manufacturing and/or processing fibrous material webs, reducing adhesion of the damp fibrous material web to a smooth surface of rotating rolls is taking on increasing significance. The forces necessary to remove the fibrous material web from the roll increasingly effect the fibrous material web and can even result in a web break.
The present invention provides a method for reducing adhesion of the fibrous material web to a rotating roll.
In accordance with the present invention, a steam cushion is produced between the roll and the fibrous material web.
Since the steam cushion reduces or substantially hinders direct contact of the fibrous material web with the surface of the roll, the forces necessary for removing the fibrous material web from the roll are reduced considerably.
The steam cushion can be produced, e.g., by heating the roll to a very high temperature that is higher than necessary for the processing of the web. For example, the temperature of the surface of the roll can be heated to a temperature that produces steam from the damp material web, e.g., temperature values greater than approximately 120xc2x0 C.
It is also possible to produce the steam cushion via heating of the roll and/or via blowing hot steam into an inlet opening between the roll and the fibrous material web.
The process is particularly applicable for use in parts of the machine in which the temperature of the fibrous material web is less than approximately 70xc2x0 C. and/or the dry content of the fibrous material web is less than approximately 60%. The method of the present invention is particularly advantageous in these areas of the machine, e.g., press sections for draining or dryer section for drying, because adhesion is particularly strong.
Accordingly, the present invention is directed to a method to reduce adhesion of a damp fibrous material web to a rotating roll. The method includes producing a steam cushion between the rotating roll and the fibrous material web.
In accordance with another feature of the present invention, the producing of the steam cushion includes heating the rotating roll to a temperature that is higher than a temperature necessary for one of drying or draining of the fibrous material web. The heating of the rotating roll may include heating the surface of the rotating roll to a temperature of greater than approximately 120xc2x0 C.
In accordance with another feature of the present invention, the method includes blowing steam into an inlet opening between the rotating roll and the fibrous material web.
In accordance with still another feature of the present invention, the temperature of the fibrous material web being guided to the rotating roll is less than approximately 70xc2x0 C. and/or the dry content of the fibrous material web being guided to the rotating roll is less than approximately 60%. Further, the rotating roll can be located within a press section for draining the fibrous material web. The rotating roll can also be located within a dryer section for drying the fibrous material web.
In accordance with yet another feature of the present invention, the fibrous material web is composed of one of a paper and textile web.
In accordance with a further feature of the present invention, the fibrous material web guided to the rotating roll has at least one of the temperature of less than approximately 70xc2x0 C. and a dry content of less than approximately 60%.
In accordance with a still further feature of the present invention, the rotating roll may be positioned in a section of a web producing machine in which the fibrous material web has at least one of the temperature less than approximately 70xc2x0 C. and a dry content less than approximately 60%. Further, the rotating roll may be positioned in at least one of a press section and a dryer section. Still further, the rotating roll may be positioned in an initial area of the dryer section. The method may further include rewetting the fibrous material web in the dryer section prior to guiding the fibrous material web to the rotating roll.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.